Plant-Perceiving Is Plant-Thinking


 Michael Marder


There is nowadays a growing scientific consensus that plants are capable of sensing variations in their environment, from changes in light to humidity gradients, from gravitropism—or the pull of gravity determining the upward growth of shoots and the downward extension of roots—to varieties of touch. Yet, the bone of contention, unlikely to be chewed through any time soon, is the so-called question of plant intelligence: Can plants think?

In the conclusion to his influential book What a Plant Knows? plant scientist Daniel Chamovitz veers on the side of caution. Although he is happy to talk about plant awareness and a whole plethora of things plants know, on matters of thinking and intelligence Chamovitz remains a skeptic. According to him, since plants have no brain, cannot suffer, and are unable to engage in a two-way “flow of meaning” with us, every attempt to attribute intelligence to them is doomed to anthropomorphic hyperbole.[i] I will not puzzle over a blatant oversight, unforgivable even to a non-philosopher, of postulating the existence of knowledge and awareness without thinking. I will, instead, take up a more difficult issue, namely the co-imbrication of thinking and perceiving.

The meaning of thinking is yet to be clarified. If this process involves nothing but abstract cogitation, elliptically implying thinking in concepts, then there is no doubt that non-human beings (and many humans, to boot) are excluded from its purview. Conceptual thought is, however, exceptionally restrictive, the confinement of thinking to conceptuality intended, above all, to maintain and reinforce the already threadbare mind-body split. “The mind thinks, while the body senses” translates into “The human thinks, while the non-human, at best, senses”. The dogmatic heritage of Cartesian skepticism expels, in the same violent gesture, us from our bodies (that, philosophically speaking, have nothing inherently human about them) and other living beings from the realm of thinking. After having been drained from the rest of corporeality, cogitation is concentrated in the brain, leaving behind body-machines, automata that move by virtue of a decision-making core localized in the head.

More recently, the brain itself has also fallen prey to machine logic. With thinking treated as a set of algorithmic operations, our “control and command center” becomes a sophisticated computing machine. This development, in turn, has unexpectedly contributed to the extension of the capacity to think to plants. As my colleague, Francisco Calvo Garzón argues, plants engage in complex algorithmic procedures in order to calculate, for instance, optimal blossoming time. Generalized, scientific reductionism holds something of a redemptive potential: instead of the metaphysical mind-body split, it subsumes the mind to the machine logic previously reserved for the body, and so “democratizes” algorithmically determined thinking now attributed to other-than-human life forms. Even as it dehumanizes us, this methodology endows plants, animals, and even colonies of bacteria or swarms with intelligence.

I do not, nevertheless, wish to conflate thinking with certain mathematical functions. My point of departure is that the body itself thinks by relating to its world and to itself. Perhaps thinking is this very dual relation, which undoubtedly includes perception—the key passageway for the body’s openness to the world and the world’s reception by the body. To be effective, the double relationality of a living extension must not only register as a conjunction of external and internal stimuli; it must also be interpreted and make sense to the organism in question. But the act of lived interpretation does not happen a posteriori, after we have been struck by signals emanating from the outside. As phenomenological philosophy has shown time and again, the sights, sounds, tactile impressions, etc. from the world around us do not arrive shorn of meaning; they come pre-interpreted as the sun setting over the sea, the blowing wind, or the touch of someone’s hand. Perceiving is already, as such, a manner of thinking. And plant-perceiving is, inherently, plant-thinking!

Of course, important differences exist between human and vegetal modes of perceiving and, therefore, thinking. The sensations a plant received from its environment are not preinterpreted in the shape of objects, which does not, however, prevent them from holding meaning for the perceiving-thinking body. There is no place for representation in the vegetal world—only for presence of light, pressure, vibrations themselves on the extension of the leaf or at the tip of a root. Far from a deficiency, this, too, has been the holy grail of phenomenology: Hegel, Husserl, and Heidegger railed against theories of “picture-thinking,” or perception understood as the inner representation of external reality, while Bergson decried modern philosophy’s impoverished approach to the world chopped up into isolated objects.

Plant-thinking, like the thinking of our own bodies, is neither conceptual nor pictorial. It is the non-theoretical contemplation of the world, a contemplation that does not keep itself separate from the contemplated but is active and engaged, sensuous and interpretative. We may glean from it the idea that thinking is not only thinking, grasped as abstract cogitation or judgment, and that the dynamism of thought is wholly indebted to this excess of thinking over and above itself, this non-identity of thinking with itself and its intimate bond to perception. Formulaically expressed: thinking ≠ thinking. Such non-identity is the exact opposite of the algorithmic functions that contemporary scientific reductionism ascribes to thinking. That is where the freedom of plants (and our own) takes refuge. If to think is to be free—not in the sense of a stale idealism but in the deeply materialist sense I have hinted at here—then plants are the most thinking and the freest of beings. And our problem is that, for much of our history, we have been dealing with them un-thinkingly, betraying both plants and ourselves. Becoming human is learning to think with our sensing-perceiving bodies, that is to say, with the world and with vegetal life.

[i] Daniel Chamovitz, What a Plant Knows? A Field Guide to the Senses of Your Garden and Beyond (Oxford: Oneworld, 2012), pp. 170-3.

3 thoughts on “Plant-Perceiving Is Plant-Thinking

  1. Excellent. And for those of us who have passed beyond the “can they / can’t they” with regard to the thinking powers of plants, Simon and Sue Lilly have shown us how to set up communication with them. Yes. Wow! See their “Tree: Essence, Spirit and Teacher” published by Capall Bann (1999) in the UK.

  2. See ‘Plant cognition’ in wikipedia. Garson and Keijzer (linked in that article ) published an article that plants meet the criteria for cognition at least on the level pf many animals. They quote ‘Darwin’s idea that plants have a control center for behavior dispersed across the root tips (a root-brain).’ The article points to other research being done in this area.

  3. Chamovitz book is entitled ‘what a plant knows’. “Knowing” I have always assumed means cognition and my dictionary also says it means intelligence. Thus the book’s conclusion that plants are unintelligent is contradicted by its own title. The data Chamovitz uses comes from laboratory experiments in which plants are made to behave like animals in a circus; the circumstances are just as artificial and unrealistic as well. It misleads some plant biologists to view plants as mere automata. Wild plants are where intelligence evolved. Their environment of intense competition and continuing stressful and highly variable circumstances requires the individual to make its own decisions. The goal for each is to try and optimise fitness; that is to maximise sibling number or at best seed number which is a suitable proxy. Intelligent behaviour is generally recognised to be behaviour that profits from experience within the individual life cycle. An ability to assess the present circumstances recall previous history and make the right and intelligent decisions for the future are part and parcel of intelligence. Numerous examples have been recorded in the past which exemplify this ability. The requirement for a brain for intelligent behaviour is rightly called brain chauvinism and unfortunately fails to recognise that plants might have a functional equivalent.

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